I have selected field in table one2many.

can i make selection field it to auto increment when i click add item or change selected field to Char ?

in my case i want make position tire being increment

iam using odoo 11

my py code :

class FleetOperations(models.Model):
    _inherit = 'fleet.vehicle'

    tire_detail = fields.One2many('tire.detail','tire_detail_id',string='Tire Detail')

class TireDetail(models.Model):
    _name = 'tire.detail'

    tire_detail_id = fields.Many2one('fleet.vehicle', string='Tire Detil')
    tire_kmdi = fields.Char(string='KMDI Tire S/N', size=64)
    is_tire_kmdi_set = fields.Boolean(string='Is KMDI Tire Srno set?')
    position_tire = fields.Selection([('pos_1', 'Posisi 1'), ('pos2', 'Posisi 2'), ('pos3', 'Posisi 3'),
                                      ('pos4', 'Posisi 4'), ('pos5', 'Posisi 5'), ('pos6', 'Posisi 6'),
                                      ('pos7', 'Posisi 7'), ('posa', 'Posisi A'), ('posb', 'Posisi B'),
                                      ('posc', 'Posisi C'), ('posd', 'Posisi D'), ('pose', 'Posisi E'),
                                      ('posf', 'Posisi F'), ('posg', 'Posisi G'), ('posh', 'Posisi H'),
                                      ('posi', 'Posisi I'), ('posj', 'Posisi J'), ('posk', 'Posisi K'),
                                      ('posl', 'Posisi L'), ('posm', 'Posisi M')], string='Posisi Ban')
    tire_size = fields.Char(string='Tire Size', size=64)
    tire_srno = fields.Char(string='Tire S/N', size=64)
    tire_issuance_date = fields.Date(string='Tire Issuance Date')

and xml

<xpath expr="///notebook/page[2]/notebook/page[2]" position="after">
      <page string="Tire Detail">
          <field name="tire_detail">
               <tree editable="top">
                   <field name="position_tire"/>
                   <field name="tire_size"/>
                   <field name="tire_srno"/>
                   <field name="tire_kmdi"/>
                   <field name="tire_issuance_date"/>
               </tree>
          </field>
      </page>
</xpath>

can anyone help me